The present invention relates generally to forage harvesters having means for processing crop material including maize kernels, these means, for instance, comprising a compressor roll assembly, operable to crack the maize kernels as well as means for processing kernel-free crops such as alfalfa or grass. The present invention also relates to a method of processing crop material including maize kernels or kernel-free crops such as alfalfa or grass.
A forage harvester is an agricultural machine for comminuting crop material for silage purposes. Such harvester is mainly used to harvest grass and maize. With grass-like materials (kernel-free) it is sufficient to slit the crop material, e.g. the stems of the plants are cut to length using a cutter, e.g. a rotating knife drum. When cutting maize the cobs may be slit into smaller size but the majority of the kernels are not broken or cracked. This reduces the nutrient value of the silaged crop as the kernels are more-or-less indigestible if not cracked. A cutterhead unit of a forage harvester is used to receive crop material harvested from the field and comminute it into forage which is fed by a blower or accelerator to a temporary container, before being stored and eventually foddered to livestock. In order to facilitate the complete digestion of the crop material, including the maize kernels, the outer skin of the kernels has to be cracked or cut. This can be done by a set of closely adjacent, co-operating compressor rolls with fluted surfaces, installed in front of the blower or accelerator, as shown for example in EP-A-0 177 995, EP-A-0 664 077 or EP-A-0 680 687.
When chopping maize, forage harvesters make use of the crop processor to crack the kernels in order to obtain a higher nutrient value of the chopped material. In that case the chopped material is thrown by the cutter-head into the crop processor, which processes (cracks) the kernels and transfers the material with sufficient speed into a blower or accelerator, which in its turn ejects the crop into a trailer or container. When chopping other kernel-free crops such as grass or alfalfa, the crop processor is redundant but the rolls may still be worn by the sand/earth in the crop material and damaged by stones therein. It is often removed from the material flow by physically removing it from the machine.
To remove the crop processor from the crop path various methods have been proposed. For example, the complete crop processor may be removed as known from DE-A-40 40 888. In DE-A-195 38 199 it is proposed not to remove the crop processor rolls but to change the direction of crop flow by means of a deflector plate. As yet another alternative, the crop processor may remain in the harvester but means are provided for shifting the crop processor unit between an active position, in which it registers with a duct from the cutter-head and an inactive position, behind the duct. Such a system is known from DE-A-42 15 696.
According to DE-A-34 07 333, DE-A-35 22 376, DE-A-196 38 034 and DE-A-33 13 673 the distance between the rolls of the crop processor is increased to leave a gap between the rolls. DE-A-34 07 333 describes allowing one roll of a roll pair to be swung away from the other of the pair. The disadvantage of this method is that one roll remains in a fixed position and is therefore still in the crop flow even when it is supposed not to be in use. DE-A-196 38 034 attempts a solution to this problem by providing a cover plate over the fixed roll when the moveable roll is in the raised, inactive position. With the crop processor known from DE-A-35 22 376 the moveable roll remains in the crop path even in the inactive position. Further, this known device uses a belt drive for both of the counter-rotating crop processor rolls. This requires the back of the belt to be used for one of the rolls. Generally, the back of a drive belt is not ideal for driving a crop processor roll particularly when the belt gets wet from contact with wet crops or mud. DE-A-33 13 673 describes a device in which the crop processor rolls are mounted on either side of a plate. The grinding action of the crop processor is therefore provided between each roll and the fixed plate. The speed differential is therefore high and cannot be set optimally. Both crop processor rolls may be moved away from the plate to take them out of the crop flow. The device also requires locating the axles of the crop processor rolls at 90xc2x0 to their normal position (i.e. vertically instead of horizontally which requires a complicated 90xc2x0 angle drive onto the crop processor rolls.
It is an objective of the present invention to provide a better arrangement for introducing compressor rolls into the stream or removing the same therefrom.
It is also an objective of the present invention to avoid the use of the back of a belt drive in order to drive one of the counter-rotating crop processor rolls.
According to the invention a forage harvester is provided having a crop processor unit located in a crop flow between a cutterhead and a blower, the crop processor unit being provided for handling crop material including kernels, the crop processor comprising a pair of counter-rotating processor rolls arranged to crack kernels between the rolls when the rolls are in a first position, both processor rolls being movable away from each other to move each roll substantially out of the crop flow.
According to an embodiment of the present invention, the drive connection to one of the pair of crop processor rolls is independent of the drive to the other roll thereof. One or both of the independent drives may be a belt drive. For example, it is preferred to drive one of the rolls more slowly than the other. Preferably, the more slowly driven roll is beneath the faster driven roll. The drive to the faster roll is preferably a belt drive. The drive to slower of the two rolls may be a further belt drive or an electric, hydraulic or pneumatic drive. A hydraulic drive is particularly preferred. The drive may operate directly on the relevant crop processor roll and may be connected to the harvester by means of a flexible power connection, e.g. a cable, conduit or pipe. The power unit for driving the roll may be, for example a hydraulic pump, a compressor or an electric power supply. It is preferred if the hydraulic drive is also used to rotate the cutterhead in the reverse direction if required. It is preferred if a cover plate moves over the lower of the two counter-rotating rolls when the rolls are moved into their widely spaced position so that the lower roll is isolated from the crop flow.
The forage harvester in accordance with the present invention may be self-propelled or may be towable by a tractor.
According to a further aspect of the present invention, a method is provided of operating a forage harvester, the harvester having a crop processor unit located in a crop flow on the output side of a cutterhead for handling crop material including kernels, the crop processor comprising a pair of counter-rotating processor rolls arranged to crack kernels between the rolls when the rolls are in a first position, the method comprising the step of:
moving both processor rolls away from each other to move each roll substantially out of the crop flow to allow the crop flow to bypass the crop processor unit.
The present invention may also include a forage harvester having a crop processor unit located in a crop flow between a cutterhead and a blower, the crop processor unit being for handling crop material including kernels, the crop processor comprising a pair of counter-rotating processor rolls arranged to crack kernels between the rolls when the rolls are in a first position, the one roll being driven by a first power drive and the second roll being driven by a second drive, the first and second drives being independently settable/controllable. One of the drives is preferably a hydraulic drive. The hydraulic drive is preferably adapted to drive the cutterhead in the reverse direction when this is required.
A forage harvester and a method of its operation in accordance with the present invention will now be described in greater detail, by way of example, with reference to the following drawings.